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It has recently been suggested that a gravitational transition of theeffective Newton's constant $G_{\rm eff}$ by about 10%, taking place 50-150Myrs ago, can lead to the resolution of both the Hubble crisis and the growthtension of the standard $\Lambda$CDM model. Hints for such an abrupt transitionwith weaker gravity at times before the transition, have recently beenidentified in Tully Fisher galactic mass-velocity data and also in Cepheid SnIacalibrator data. Here we use Monte-Carlo simulations to show that such atransition could significantly increase (by a factor of 3 or more) the numberof long period comets (LPCs) impacting the solar system from the Oort cloud(semi-major axis of orbits $\gtrsim 10^4AU$). This increase is consistent withobservational evidence from the terrestrial and lunar cratering ratesindicating that the impact flux of kilometer sized objects increased by atleast a factor of 2 over that last 100 Myrs compared to the long term average.This increase may also be connected with the Chicxulub impactor event thatproduced the Cretaceous-Tertiary (K-T) extinction of 75% of life on Earth(including dinosaurs) about 66 Myrs ago. We use Monte-Carlo simulations to showthat for isotropic Oort cloud comet distribution with initially circularorbits, random velocity perturbations (induced eg by passing stars and/orgalactic tidal effects), lead to a deformation of the orbits that increasessignificantly when $G_{\rm eff}$ increases. A 10% increase of $G_{\rm eff}$leads to an increase in the probability of the comets to enter the loss coneand reach the planetary region (pericenter of less than 10AU) by a factor thatranges from 5% (for velocity perturbation much smaller than the comet initialvelocity) to more than 300% (for total velocity perturbations comparable withthe initial comet velocity).

Is the Hubble crisis connected with the extinction of dinosaurs?